Thermal chemical vapor deposition (CVD) is a method used in the fabrication of integrated circuitry for depositing one or more insulative, conductive, or semiconductive materials onto a substrate. First and second deposition precursors are provided to a chamber within which a substrate is received. The substrate and/or chamber are provided at a desired elevated temperature, and the precursors react to deposit a suitable material onto the substrate. More than two deposition precursors and one or more carrier gases might also be used.
One prior art thermal CVD process uses TiCl4 and NH3 as deposition precursors in depositing TiN. The desired reaction by-product is HCl which is exhausted from the chamber. However, other reaction by-products are created, and regardless chlorine can undesirably remain in the deposited material.
One existing manner of minimizing chlorine incorporation includes repeating a sequence of deposition steps. In a first step, TiCl4 and NH3 are flowed to the substrate to deposit a layer of TiN which is thinner than the desired ultimate thickness. This is followed by an inert purge gas flow to remove unreacted precursor and reaction by-product. After the purge step, NH3 is flowed to the substrate with the effect being chlorine removal by formation of HCl and additional nitrogen atom incorporation into the previously deposited material. This is followed by another inert purge step, this one typically lasting from 5 to 10 seconds. The overall process is repeated until a layer of desired thickness is deposited onto the substrate. Existing equipment in which such is conducted is available from Tokyo Electron (TEL), for example the “TRIAS TiN System” or the “TEL Unity System”. Such include a plurality of filtering devices in the form of traps to collect unreacted precursors and reaction by-products prior to flowing to a vacuum pump.
While embodiments disclosed herein were motivated in addressing the above issues particular to a thermal CVD of TiN, the disclosure herein is in no way so limited.